The subject matter disclosed herein relates to industrial process control systems, methods and devices. Specifically, the disclosed subject matter relates to industrial control devices which include a plurality of modules, such as, but not limited to, I/O (Input/Output) modules, where it is desired to remove and insert a module into a backplane component of the control device without interrupting, or minimally interrupting, data communications between other modules attached to the backplane.
FIG. 1 shows a conventional point module arrangement for an industrial process control device. As shown, the device includes a mounting base 2, a removable terminal block (RTB) 6, a point adaptor 8 and a point module 4. Applications of this architecture include industrial controllers, distributed I/O controllers, machine controllers, field devices, etc. Multiple point modules can be attached adjacently to provide a multi-module system, where the mounting bases incorporate an active backplane which provides power to the point modules and includes the necessary interface to provide data communications between the point modules, as well as data communications with the point adapter which communicates with an external network, other device, and/or industrial controller, etc.
With reference to FIG. 2, illustrated is a conventional point-to-point backplane module arrangement for a controller including a plurality of I/O modules 22, 24 and 26, and an Ethernet communication adapter 20. As shown, the arrangement includes a point-to-point backplane including mounting bases 28, 30 and 32 for each of the I/O modules 22, 24 and 26, respectively. Importantly, if an I/O module is disengaged, i.e., removed, from the backplane, data communications connectivity is broken between the modules adjacent to the removed module, as is shown with I/O module 24 detached from mounting base 30 in FIG. 2.
With reference to FIG. 3, illustrated is a conventional multi-point backplane module arrangement for a controller including a plurality of I/O modules 40, 42 and 44 and an Ethernet communication adapter 20. As shown, the arrangement includes a multi-point backplane including mounting bases 46, 48 and 50 for each of the I/O modules 40, 42 and 44, respectively. Importantly, if an I/O module is removed or inserted, i.e., removed from the backplane or inserted to the backplane, data communications connectivity is maintained with the downstream I/O modules because a multi-point communications protocol, e.g., CAN (Controller Area Network) (DeviceNet), is used for data communications between the I/O modules. For example, as shown in FIG. 3, I/O module 40 is removed from mounting base 46 which does not interrupt communications between point adapter 20, I/O module 42 and 44.
A point-to-point backplane arrangement, as shown in FIG. 2, typically can achieve higher data communication rates, as compared to a multi-point backplane arrangement, as shown in FIG. 3. For example, a point-to-point Ethernet based data communication network typically achieves 100 Mbps-1 Gbps, and a multi-point based data communication network typically achieves 1 Mbps for a CAN bus based network and 50 Mbps for a RS485 based network. Therefore, from a data communication speed perspective, it is desirable to use a point-to-point backplane arrangement. However, as discussed above with reference to FIG. 2, a conventional point-to-point backplane arrangement has the disadvantage of not providing RIUP (Removal and Insertion Under Power) functionality while maintaining data communications with modules downstream of a removed point module.
This disclosure and the exemplary embodiments described herein provide a RIUP point-to-point module arrangement with relatively minimum or no loss of data communications with downstream point modules with the removal of a point module from a backplane.